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Solar external heat exchanger
Solar / Opt. functions / Add new function... / Ext. HX
Adjustment
channel
Description
Adjustment range /
selection
Factory setting
Relay
Relay selection
system dependent system dependent
Min. speed
Minimum speed
(20) 30 … 100 %
30 %
Store
Store sensor selection
system dependent 1
Sen. Ext. HX Reference sensor ext. HX
system dependent system dependent
Target
temperature
Target temperature option
Yes, No
No
Sensor
Target temperature reference
sensor
system dependent system dependent
Target temp. Target temperature
15 … 95 °C
60 °C
D
Ton
Switch-on temperature difference 1.0 … 20.0 K
10.0 K
D
Toff
Switch-off temperature difference 0.5 … 19.5 K
5.0 K
Overrun
Overrun time
1 … 15 min
2 min
This function is used for linking loading circuits that are separated by an external
heat exchanger.
The allocated relay is energised if one of the selected stores is being loaded and
there is a temperature difference between the sensor of the corresponding store
and the solar fl ow.
Any number of the solar stores can be selected.
The relay is switched off if this temperature difference falls below the adjusted
switch-off difference.
In contrast to the bypass function, a differential control between Sen. Ext. HX and
the store temperature can be carried out by means of the heat exchanger relay.
The reference sensor can be arbitrarily allocated.
In systems in which stores are equipped with their own loading pumps, the relay
“external heat exchanger“ controls the primary circuit pump.
The heat exchanger is protected by an antifreeze function. If the temperature at
the external HX sensor Sen. Ext. HX falls below 10 °C, the secondary pump
will be activated at 100 % speed. The controller will then unload the store with
the lowest priority. If the temperature exceeds 12 °C, the secondary pump will be
switched off. The heat exchanger antifreeze function will also become active when
there is no solar loading in progress.
Note:
In order to prevent the stores from freezing while the antifreeze function
of the heat exchanger is active, an afterheating has to be available for the
stores.
Note:
Because of the special hydraulics in systems with 2 collectors, the target
temperature function will not work properly there.
Summary of Contents for SC5.14
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